Everything you need to know about the VAZ 2101 thermostat

The slightest violation of the thermal regime of an automobile engine can cause its failure. The most dangerous factor for the power plant is overheating. Most often, it occurs due to a malfunction of the thermostat - one of the main elements of the cooling system.

Thermostat VAZ 2101

"Kopecks", like other representatives of classic VAZs, were equipped with domestically produced thermostats, produced under the catalog number 2101-1306010. The same parts were installed on cars of the Niva family.

The thermostat is used to maintain the optimum temperature of the engine

Why you need a thermostat

The thermostat is designed to maintain the optimal thermal regime of the engine. In fact, it is an automatic temperature controller that allows you to warm up a cold engine faster and cool it when heated to the limit value.

For the VAZ 2101 engine, the optimum temperature is considered to be in the range of 90–115 ^oC. Exceeding these values ​​is fraught with overheating, which can cause the cylinder head gasket (cylinder head) to burn out, followed by depressurization of the cooling system. Moreover, the engine can simply jam due to the increase in the size of the pistons caused by high temperature.

If the cylinder head gasket is damaged, the cooling system is depressurized

Of course, this will not happen with a cold engine, but it will not be able to work stably until it warms up to the optimum temperature. All design characteristics of the power unit regarding power, compression ratio and torque directly depend on the thermal regime. In other words, a cold engine is not able to give the performance that is declared by the manufacturer.

Design

Structurally, the VAZ 2101 thermostat consists of three blocks:

• non-separable body with three nozzles. It is made of metal, which has good chemical resistance. It can be copper, brass or aluminum;
• thermoelement. This is the main part of the device, which is located in the central part of the thermostat. The thermoelement consists of a metal case made in the form of a cylinder and a piston. The inner space of the part is filled with a special technical wax, which tends to actively expand when heated. Increasing in volume, this wax pushes a spring-loaded piston, which, in turn, actuates the valve mechanism;
• valve mechanism. It includes two valves: bypass and main. The first serves to ensure that the coolant has the opportunity to circulate through the thermostat when the engine is cold, bypassing the radiator, and the second opens the way for it to go there when heated to a certain temperature.
  

  The bypass valve opens at low temperatures and allows the coolant to pass directly into the engine, and the main valve when heated to a certain temperature, directing the liquid along a large circuit to the radiator

The internal structure of each block is of only theoretical interest, because the thermostat is a non-separable part that changes entirely.

The thermostat consists of the following elements: 1 - inlet pipe (from the engine), 2 - bypass valve, 3 - bypass valve spring, 4 - glass, 5 - rubber insert, 6 - outlet pipe, 7 - main valve spring, 8 - main valve seat valve, 9 - main valve, 10 - holder, 11 - adjusting nut, 12 - piston, 13 - inlet pipe from the radiator, 14 - filler, 15 - clip, D - fluid inlet from the engine, R - fluid inlet from the radiator, N - fluid outlet to the pump

Operating principle

The cooling system of the VAZ 2101 engine is divided into two circles through which the refrigerant can circulate: small and large. When starting a cold engine, the liquid from the cooling jacket enters the thermostat, the main valve of which is closed. Passing through the bypass valve, it goes directly to the water pump (pump), and from it back to the engine. Circulating in a small circle, the liquid does not have time to cool, but only heats up. When it reaches a temperature of 80–85 ^oWith the wax inside the thermoelement begins to melt, increasing in volume and pushing the piston. At the first stage, the piston only slightly opens the main valve and part of the coolant enters the large circle. Through it, it moves to the radiator, where it cools down, passing through the tubes of the heat exchanger, and already cooled down, it is sent back to the engine cooling jacket.

The degree of opening of the main valve depends on the temperature of the coolant

The main part of the liquid continues to circulate in a small circle, but when its temperature reaches 93–95 ^oC, the thermocouple piston extends as far as possible from the body, fully opening the main valve. In this position, all the refrigerant moves in a large circle through the cooling radiator.

Video: how the thermostat works

Car thermostat, how it works

Which thermostat is better

There are only two parameters by which a car thermostat is usually chosen: the temperature at which the main valve opens and the quality of the part itself. Regarding the temperature, the opinions of car owners differ. Some want it to be higher, i.e., the engine warms up less time, while others, on the contrary, prefer to warm up the engine longer. The climatic factor should be taken into account here. When operating the car in normal temperature conditions, a standard thermostat that opens at 80 ^oC. If we are talking about cold regions, then it is better to choose a model with a higher opening temperature.

As for the manufacturers and quality of thermostats, according to the reviews of the owners of "kopecks" and other classic VAZs, parts made in Poland (KRONER, WEEN, METAL-INKA), as well as in Russia with Polish thermoelements ("Pramo") are the most popular. It is not worth considering temperature controllers made in China as a cheap alternative.

Polish-made WEEN thermostats have proven themselves among the owners of the VAZ 2101

Where is the thermostat

In the VAZ 2101, the thermostat is located in front of the engine compartment on the right side. You can easily find it by the thick cooling system hoses that fit it.

In a VAZ 2101 car, the thermostat is located in the engine compartment on the right

Malfunctions of the VAZ 2101 thermostat and their symptoms

The thermostat can have only two breakdowns: mechanical damage, due to which the device body has lost its tightness, and jamming of the main valve. It makes no sense to consider the first malfunction, since it happens extremely rarely (as a result of an accident, inept repair, etc.). In addition, such a breakdown can be determined even by visual inspection.

The jamming of the main valve happens much more often. Moreover, it can jam both in the open and in the closed or middle position. In each of these cases, the signs of its failure will be different:

• the engine takes a long time to warm up. According to the passport data of the VAZ 2101, the power plant should warm up to operating temperature in 4–7 minutes, depending on the ambient temperature. If the motor does not fit within this time, most likely, the main valve is stuck in the open position. In this case, from the moment the engine starts, the coolant passes in a large circle, i.e. through the radiator, where its temperature decreases. To confirm or refute your suspicions, you need to start a cold engine, wait 1-2 minutes and touch the rubber hose connecting the thermostat and the upper radiator tank with your hand. If it is warm, the valve is definitely stuck in the open or middle position. It is possible to continue operating the car in such cases, but there is no guarantee that the valve will not move in the opposite direction and will not “stick”, blocking the flow of refrigerant to the radiator;
  

  If the upper radiator hose becomes warm after 1-2 minutes of engine operation, then the main thermostat valve is stuck open
• the engine warms up earlier than 4 minutes, and then there is a clear overheating, confirmed by the readings of the coolant temperature sensor. In this case, the valve is stuck in the closed position. To confirm, let's turn to the same pipe going from the thermostat to the top of the radiator. If it remains cold after four minutes, the thermostat is faulty. It is impossible to continue driving with such a breakdown, otherwise the engine will fail.;
• the temperature of the operating power unit is unstable. If the valve is stuck in an intermediate position, it is almost impossible to diagnose a thermostat malfunction without dismantling it. But if you notice that the arrow of the temperature sensor device is constantly changing its position (with a known good sensor and device), the thermostat is probably the reason for this. Such a breakdown does not pose a serious threat to the engine, however, it must be eliminated as soon as possible.

Why the thermostat fails and is it possible to restore its performance

Practice shows that even the most expensive branded thermostat lasts no more than four years. As for cheap analogs, problems with them can arise even after a month of operation. The main causes of device breakdowns include:

• use of low-quality coolant;
• the presence in the cooling system of oxidation products, water, dirt;
• manufacturing defects.

From personal experience, I can give an example of using cheap antifreeze, which I bought for some time in the automotive market for a spill from a “verified” seller. Having found signs of the thermostat jamming in the open position, I decided to replace it. At the end of the repair work, I brought the defective part home to check and, if possible, bring it to working condition by boiling it in engine oil (why, I will tell later). When I examined the inner surface of the device, the thought of using it someday again disappeared from me. The walls of the part were covered with multiple shells, indicating active oxidative processes. The thermostat, of course, was thrown away, but the misadventures did not end there. After 2 months, there were signs of breaking through the cylinder head gasket and getting coolant into the combustion chambers. But that's not all. When removing the head, shells were found on the mating surfaces of the cylinder head, block, and also on the windows of the channels of the cooling jacket. At the same time, a strong smell of ammonia emanated from the engine. According to the master who performed the “autopsy”, I am not the first and far from the last who had or will have to regret saving money on coolant.

As a result, I had to buy a gasket, a block head, pay for its grinding, as well as all dismantling and installation work. Since then, I have been bypassing the car market, buying only antifreeze, and not the cheapest.

Poor quality coolant corrodes the elements of the cooling system

Corrosion products and various debris are most often the cause of the main valve jamming. Day after day they are deposited on the inner walls of the case and at some point begin to interfere with its free movement. This is how "sticking" happens.

As for marriage, it occurs quite often. Not a single car shop, not to mention sellers in the car market, will guarantee that the thermostat you bought will open and close at the temperature indicated in the passport, and generally work correctly. That is why ask for a receipt and do not throw away the packaging in case something goes wrong. Moreover, before installing a new part, do not be too lazy to check it.

Dirt and oxidation deposits cause the main valve to jam

A few words about boiling the thermostat in oil. This method of repair has been practiced by our car owners for a long time. There is no guarantee that the device will work like new after such simple manipulations, but it's worth a try. I have done similar experiments twice, and in both cases everything worked out. I would not recommend using a thermostat restored in this way, but as a spare part thrown into the trunk “just in case”, believe me, it can come in handy. In order to try to restore the device, we need:

• engine oil (not working out);
• a metal container that would hold the thermostat so that it is completely covered with oil;
• gas or electric stove;
• aerosol WD-40 or equivalent;
• carburetor cleaner.

First of all, it is necessary to liberally treat the inner walls of the thermostat and the valve mechanism with carburetor cleaning fluid. After waiting 10-20 minutes, immerse the device in a container, pour oil so that it covers the part, put the bowl on the stove. Boil the thermostat for at least 20 minutes. After boiling, let the oil cool down, remove the thermostat, drain the oil from it, wipe it with a dry cloth. After that, you can spray the valve mechanism with WD-40. At the end of the restoration work, the temperature controller must be checked in the manner described below.

What to do if the thermostat is stuck closed on the road

On the road, a thermostat valve jammed in a small circle can cause a lot of trouble, ranging from a disrupted trip to the need for urgent repairs. However, in some cases, these troubles can be avoided. Firstly, it is important to notice an increase in the temperature of the coolant in time and prevent critical overheating of the power plant. Secondly, if you have a set of keys, and there is an auto shop nearby, the thermostat can be replaced. Thirdly, you can try to wedge the valve. And finally, you can slowly drive home.

For better understanding, I will again give an example from my experience. One frosty winter morning, I started my "penny" and calmly went to work. Despite the cold, the engine started easily and warmed up fairly quickly. Having driven about 3 kilometers from the house, I suddenly noticed trickles of white steam from under the hood. There was no need to go through the options. The arrow of the temperature sensor has exceeded 130 ^oS. After turning off the engine and pulling to the side of the road, I opened the hood. Speculation about a thermostat malfunction was confirmed by a swollen expansion tank and a cold branch pipe of the upper radiator tank. The keys were in the trunk, but the nearest car dealership was at least 4 kilometers away. Without thinking twice, I took the pliers and hit them several times on the thermostat housing. Thus, according to the "experienced", it is possible to wedge the valve. It really helped. Already a few seconds after starting the engine, the upper pipe was hot. This means that the thermostat has opened a large circle. Delighted, I got behind the wheel and calmly drove to work.

Returning home, I did not think about the thermostat. But as it turned out, in vain. After driving halfway, I noticed the temperature sensor device. The arrow again approached 130 ^oC. With "knowledge of the matter" I again began to knock on the thermostat, but there was no result. Attempts to wedge the valve lasted about an hour. During this time, of course, I froze to the bone, but the engine cooled down. In order not to leave the car on the track, it was decided to slowly drive home. Trying not to overheat the motor over 100 ^oC, with the stove turned on at full power, I drove no more than 500 m and turned it off, letting it cool. I got home in about an hour and a half, driving about five kilometers. The next day I replaced the thermostat on my own.

How to check the thermostat

You can diagnose the thermostat without the involvement of specialists. The procedure for checking it is quite simple, but for this the part will need to be dismantled. We will consider the process of removing it from the engine below. And now imagine that we have already done this and the thermostat is in our hands. By the way, it can be a new, just bought device, or restored by boiling in oil.

To test the thermostat, we only need a kettle of boiling water. We place the device in the sink (sink, pan, bucket) so that the pipe connecting the part to the engine is at the top. Next, pour boiling water from the kettle into the nozzle with a small stream and observe what is happening. First, water must pass through the bypass valve and pour out of the middle branch pipe, and after heating the thermoelement and actuation of the main valve, from the lower one.

Video: checking the thermostat

Checking the car thermostat

Replacing the thermostat

You can replace the temperature controller on a "penny" with your own hands. Of the tools and materials for this you will need:

• thin slotted or large Phillips screwdriver (depending on the type of clamps that tighten the ends of the hoses);
• wrench 13 mm;
• a container for collecting coolant;
• dry rag;
• coolant (topping up).

Removing the thermostat

The dismantling procedure is as follows:

1. Set up the car on a level surface. If the engine is hot, let it cool completely.
2. Open the hood, unscrew the caps on the expansion tank and on the radiator.
   

   To drain the coolant faster, you need to unscrew the caps of the radiator and expansion tank
3. Place a container under the refrigerant drain plug.
4. Unscrew the plug with a 13 mm wrench.
   

   To unscrew the cork, you need a 13 mm wrench
5. We drain part of the liquid (1–1,5 l).
   

   Drained coolant can be reused
6. We tighten the cork.
7. Wipe up spilled liquid with a rag.
8. Using a screwdriver, loosen the tightening of the clamps and, one by one, disconnect the hoses from the thermostat nozzles.
   

   Clamps are loosened with a screwdriver
9. We remove the thermostat.
   

   When the clamps are loosened, the hoses can be easily removed from the nozzles

Installing a new thermostat

To install a new part, we perform the following work:

1. We put the ends of the hoses of the cooling system on the thermostat pipes.
   

   To make the fittings easier to put on, you need to moisten their inner surfaces with coolant.
2. Tighten the clamps tightly, but not all the way.
3. Pour coolant into the radiator to the level. We twist the caps of the tank and radiator.
4. We start the engine, warm it up and check the operation of the device by determining the temperature of the upper hose by hand.
5. If the thermostat is operating normally, turn off the engine and tighten the clamps.

Video: replacing the thermostat

how to change thermostat on classic 2106

As you can see, there is absolutely nothing complicated either in the design of the thermostat or in the process of replacing it. Periodically check the operation of this device and monitor the temperature of the coolant, then your car engine will last a very long time.